SOME OF THE "LOWER ORDERS" 207 



are readily accounted for ; for they are manifestations of 

 inherent growth changes which, having started, are free 

 to go on increasing in ampHtude unless, and until, checked 

 by natural selection. There is nothing unreasonable or 

 improbable in this interpretation ; on the contrary, it 

 embraces also many other features hitherto ignored, but 

 no less demanding an explanation. Such, for example, 

 as the infinite variety of form and sculpture which the 

 scales of the wings and the eggs display. These are 

 details visible only by the aid of the microscope, but they 

 demand explanation as much as the more obvious 

 characters. Moreover they have the advantage of belong- 

 ing to a set of characters which cannot in any way in- 

 fluence the choice, if choice there be, in the selection 

 of mates, nor are they of a nature likely to affect the 

 results of the struggle for existence. Of these characters, 

 then — the sculpturing of the egg-shell and of the scales, 

 the " nervation " of the wings, and coloration — we can 

 say no more than that they are idiosyncrasies of growth, 

 free to develop in any direction unless, and until, checked 

 by natural selection, which will speedily eliminate dis- 

 harmonies with the environm.ent. 



